Preparation of 2,2,3-trichloroheptafluorobutane



United States Patent PREPARATION OF 2,2,3-TRICHLOROHEPTA- FLUOROBUTANE Charles F. Baranauelras and William E. Ashton, Niagara Falls, N. Y., assignors to Hooker Chemical Corporation, Niagara Falls, N. Y., a corporation of New York N0 Drawing. Application August 13, 1956 Serial N0. 603,826

8 Claims. (Cl. Z60-653.7)

This invention relates to the preparation of a perhalobutane, and more particularly relates to the preparation of 2,2,3-trichloroheptafluorobutane. by treating a straight chain perhalocarbon containing four carbon atoms with a fluorinating agent.

The compound 2,2,3-trichloroheptafluorobutane prepared by the process of this invention is useful as a solvent in a variety of reactions. Further, the compound is useful as a heat transfer agent due to its chemical inertness, its boiling point and other physical properties.

In United States Patent 2,436,357 Gochenour et al. described the fluorination of hexachlorobutadiene in such manner as to eliminate one of the double bonds, and cause theshift of the other double bond to the C -C carbon atoms while substituting fluorine atoms for some of the chlorine atoms present in the original molecule, thereby to form dichlorohexafluorobutene-2, and monochloroheptafluorobutene-2. The fluorinating agent employed according to Gochenour et al. is a composition containing an antimony halide, hydrogen fluoride, and elemental chlorine.

We have now found that when starting with a perhalocarbon represented by the formula CXCXCXCX in which X consists of two or three atoms of fluorine, chlorine or a mixture thereof and X consists of one or two atoms of chlorine, in admixture with a fluorinating agent containing an antimony halide, hydrogen fluoride, and elemental chlorine and While maintaining the temperature of the reaction zone between about 200 degrees and about 300 degrees centigrade for a contact time of less than ten hours, 2,2,3-trichloroheptafluorobutane may be prepared in good yield.

The reactions illustrated in the following equations show the preparation of the desired compound 2,2,3-trichloroheptafluorobutane by reacting a straight chain perhalocarbon containing four carbon atoms, for example a butadiene, such as hexachlorobutadiene; a butene, such as 2,3-dichlorohexafluorobutene-Z and a butane, such as 2,2,3,3-tetrachlorohexabutane with a fluorinating agent containing an antimony halide, hydrogen fluoride and elemental chlorine.

CCI2=O Cl-O 01:0 011 7H]? 2012 Hexachlorobutadiene 2,2,3-Trichloreheptafluorobutane.

SbChFt-x heat 2,862,036- Patented Nov. 25, 1958 EXAMPLE 1 A Monel-clad autoclave that had been pre-cooled to about minus 50 degrees centigrade in the absence of moisture was charged with 1,398 parts of 2,3-dichlorohexafluorobutene-Z, 1,074 parts of antimony trifluoride, and 852 parts of chlorine and was sealed. The autoclave was then inserted into a rocking type heating jacket and the temperature was recorded automatically from a thermocouple inserted in the thermowell of the autoclave.

The reactor was heated rapidly to a temperature of about 250 degrees centigrade, and maintained at this temperature for seven hours and attained a pressure of approximately 1200 p. s. i. g. Thereafter the reactor was cooled rapidly to below Zero and the contents vented into a collection system consisting of a series of caustic traps to neutralize the acidic components then into a Dry-Ice trap to collect any low boiling products. After the initial venting had subsided, the reactor was heated to degrees centigrade to distill over the higher boiling products to the collection system. The antimony salts remaining in the reactor were cooled to room temperature and were decomposed by the addition of 1,000 milliliters of hydrochloric acid. The decomposed salt slurry was extracted with carbon tetrachloride to insure complete recovery of the organic products. The crude product was washed, dried and fractionated. The desired product, 2,2,3-trichloroheptafluorobutane (82.7% yield), was collected over a temperature range of 96 degrees to 98 degrees centigrade and then was treated with moist soda ash to remove any acidic materials to provide a clear water-like liquid having a refractive index of 1.3525: 0.0002 at 20 degrees centigrade.

EXAMPLE 2 In an apparatus similar to that described in connection with Example 1, 1,398 parts of 2,3-dichlorohexafluorobutene-Z, 1,800 parts of antimony pentachloride, 300 parts of chlorine and 600 parts of hydrogen fluoride were charged into the Monel clad autoclave.

The reactor contents were heated rapidly to a temperature of 250 degrees centigrade and maintained at this temperature for seven hours. The product, 868 parts of 2,2,3-trichloroheptafluorobutane (80.5% yield) was obtained in a manner after that described in Example 1.

EXAMPLE 3 In an apparatus and under conditions similar to that described in connection with Example 1, 261 parts of hexachlorobutadiene, 1200 parts of antimony pentachloride, 600 parts of hydrogen fluoride and 200 parts of chlorine were charged into the autoclave.

The reactor contents were heated rapidly to a temperature of 250 degrees centigrade and maintained at this temperature for four hours. The product, 133 parts of 2,2,3-trichloroheptafluorobutane (46.2% yield) was obtained in a manner after that described in Example 1.

3 EXAMPLE 4 In an apparatus, and under conditions similar to that described in connection with Example 1, 517 parts of 2,2,3,3-tetrachlorohexafiuorobutane, 600 parts of antialthough periods of from less than eight hours are preferred.

Agitation is desirable in the process of this invention especially since the reactants are not mutually soluble in 5 one another. The reaction slows down appreciably with- 33; fig ggi a ggig i i g figg gzf of hydrogen fluoride out agitation of the liquid. Agitation may be accom- The reactor contents were heated rapidly to a temperpllshed by mechttmcal such as by mechamctil ature of250 degrees centigrade for five hours. "The prod- Stu-ism and pulsantlg or rock.mg The fluon' uct, 180 parts of 2,2,3-trichloroheptafluorobutane (37% name agent contams an antlmoily halide i hydrogen yield) was obtained in a manner after that described in fluoride and/qr elemental q dependmg .upon the Example 1, startmg material as shown 1n the above equations.

The preferred antimony hahdes are the antimony EXAMPLE 5 chlorofluorides such as antimony dichlorotrifluoride. Octachlorobutene-Z (0.99 moles, 329 grams) and anti- These haltdes t be Prepared y reacting antimony mony trifluoride (3 moles 536 grams) were placed in pentachlorlde with hydrogen fluoride at temperatures aMonel autoclave with a capacity of three liters. The about 150 degrees Penttgtade or by reactmg antlmony autoclave and contents were gradually heated with agitafluondes with q a at ebout 100 degrees centlgrade tion over a 25 hour period to approximately 200 degrees h Process P this mventlon y conducted batch centigrade and maintained at this temperature for an wtse'or contmuously' The teactton Preferably additional five hours The bomb and contents were ducted under the vapor pressure of the reactants at the .cooled to 50 degrees centigrade and the pressure within tempetatulje m f Whtch keep? the reactants the autoclave was released by venting it into a receiver stantlfttty m the hquld Phase and tttcteases the mutuel cooled in a. bath of Dry Ice and ethanol. After cooling sotublhty g W e we have mdlcated that t the bomb and contents to below 20 degrees Centigrade, mony dlchlorotnfluoride is the preferred antlmony halide, the material remaining in the bomb was washed four 1t t be te to those sktued e art that the times with 6 N hydrochloric acid, once with watenvonce pretflse composltton of the antlmony hahde may Vary with dilute aqueous sodium carbonate, and combined dunns the course of the reacttonwith the material collected in the receiver. After drying, It IS to e undetstood t the above desenbed this material was rectified. 2,3-dichlorohexafluorobuamples are slmPty lnustratlve of the application of the -2 was btaingd i 57 percent i 1d 3O principlesof the invention. Numerous other modifica- The following table contains the results of examples tions y be readily devised y those Skilled in the art of the process of this invention wherein reaction condiwhich will embody the principles of the invention and tions were varied. fall within the spirit and scope thereof.

Table Example O4C12Fu, SbCk, SbF; HF, 01, Temp., Press, Reaction C4C13F7, Residual, Yield No. pts. pts. pts. pts. pts. C. p. s. i. g time, pts. pts. 04013F7, hrs. percent 170 300 5 168 73 33.2 170 275 5 254 st. 2 50.8 170 250 2, 950 5 375 54 71. 7 304 250 1, 200 5 406 63. 5 7s. 7 192 225 2, 180 5 289 11s 62. 5 210 200 5 11 236 852 250 700 7 875 493 70. 3

It is critical that the temperature range in the process We claim: of this invention be between about 200 degrees and about 1. A process for making 2,2,3-trichloroheptafluorobu- 300 degrees centigrade, although the preferred tempertane which includes: heating a perhalocarbon selected ature range is between about 225 degrees and about 275 from the group consisting of hexachlorobutadiene; 2,3- degrees centigrade. At temperatures above 275 degrees dichlorohexafluorobutene-Z; 1,2,3-trichloropentafluorobucentigrade, the amount of 2,3-dichlorooctafiuorobutane tene-Z; l,1,2,3-tetrachlorotetrafiuorobutene-2; 1,l,1,2,3- produced becomes appreciable and results in a decreased pentachlorotrifluorobutene-Z; l,l,2,3,4,4 hexachlorodb, yield of the desired product. At temperatures below fiuorobutene-2 and 1,l,l,2,3,4,4,4-octachlorobutene-2, about 225 degrees centigrade, the yield of product drops 55 with a fluorinating agent containing an antimony halide, olf sharply and most of the starting material is recovered hydrogen fluoride and elemental chlorine while mainas 2,2,3,3-tetrachlorohexafluorobutane, which may be retaining the reaction temperature between about 200 decycled to produce the desired product. grees and 300 degrees Centigrade for a contact time of The contact time of the starting material with the less than ten hours. fiuorinating agent may be varied to some extent without 2. The process according to claim 1 wherein said noticable sacrifice of advantageous high efliciency of perhalocarbon is a perhalobutadiene. operation. However, if contact time is excessive, the 3. The process according to claim 1 wherein said capacity of the reactor is low thereby causing economic perhalocarbon is a perhalobutene. disadvantages in the operation. On the other hand, if 4. The process according to claim 1 wherein said anticontact time is too short, the reaction of starting mamony halide is an antimony chlorofluoride. terial to form desired product may be incomplete thereby 5. A process for making 2,2,B-trichloroheptafluorobuentaining high cost of recovering and recycling unretane which includes: heating a perhalocarbon selected acted material to subsequent operation. Accordingly, from the group consisting of hexachlorobutadiene; 2,3- the time of contact is determined by balancing the ecodichlorohexafluorobutene-Z; 1,2,3 trichloropentafluoronomic advantage of high reactor throughput obtained at butene-Z; 1,1,2,3-tetrachlorotetrafiuorobutene-2; 1,l,l,2, short contact times against the cost of recovery of unre- 3-pentachlorotrifluorobutene-Z; l,1,2,3,4,4-hexachlorodiacted starting material. It has been found that to obtain fiuorobutene-Z and 1,l,1,2,3,4,4,4 octachlorobutene 2 optimum conditions, passage of the starting material-in with a fiuorinatingagent containing an antimony halide, contactwith the fluorinating agent should be'controlled hydrogen fluoride and elemental chlorine while maintdefiect a residence or contact time of less than-ten'hours 7 taining the reaction temperature between about 225 .de

grees and 275 degrees centigrade for a contact time of less than ten hours.

6. A process for making 2,2,3-trichloroheptafluorobutane which includes: heating a perhalocarbon represented by the formula CF -CC1=CC1-CF with a fluorinating agent containing an antimony halide, hydrogen fluoride and elemental chlorine while maintaining the reaction temperature between about 225 degrees and 275 degrees centigrade for a contact time of less than ten hours.

7. A process for making 2,2,3-trichloroheptafluorobutane which includes: heating hexachlorobutadiene with a fluorinating agent containing an antimony halide, seven moles of hydrogen fluoride and two moles of chlorine per mole of starting material while maintaining the reaction temperature between about 225 degrees and 275 degrees centigrade for a contact time of less than ten hours.

8. A process for making 2,2,3-trichloroheptafluorobutane which includes: heating a perhalocarbon selected from the group consisting of hexachlorobutadiene; 2,3- dichlorohexafluorobutene-Z; 1,2,3-trichloropentafluorobutene-2; 1,1,2,3-tetrachlorotetrafluorobutene-2; 1,1,1,2,3- pentachlorotrifluorobutene-Z; 1,1,2,3,4,4 hexachlorodifluorobutene-Z and 1,1,1,2,3,4,4,4 octachlorobutene 2 with a fluorinating agent containing an antimony dichlorotrifluoride, hydrogen fluoride and elemental chlorine while maintaining the reaction temperature between about 225 degrees and 275 degrees centigrade for a contact time of less than ten hours.

References Cited in the file of this patent UNITED STATES PATENTS 2,062,743 Daudt et al. Dec. 1, 1936 2,436,357 Gochenour et a1 Feb. 17, 1948 FOREIGN PATENTS 740,418 Great Britain Nov. 9, 1955 

1. A PROCESS FOR MAKING 2,2,3-TRICHLOROHEPTAFLUOROBU TANE WHICH INCLUDES: HEATING A PERHALOCARBON SELECTED FROM THE GROUP CONSISTING OF HEXACHLOROBUTADIENE; 2,3DICHLOROHEXAFLUOROBUTENE-2; 1,2,3-TETRACHLOROTETRAFLUOROBUTENE-2; 1,1,2,3-TETRACHLOROTETRAFLUOROBUTENE-2; 1,1,1,2,3PENTACHLOROTRIFLUOROBUTENE-2; 1,1,2,3,4,4-HEXACHLORODIFLUOROBUTENE-2, AND 1,1,1,2,3,4,4-OCTACHLOROBUTENE-2, WITH A FLUORINATING AGENT CONTAINING AN ANTIMONY HALIDE, HYDROGEN FLUORIDE AND ELEMENTAL CHLORINE WHILE MAINTAINING THE REACTION TEMPERATURE BETWEEN ABOUT 200 DEGREES AND 300 DEGREES CENTIGRADE FOR A CONTACT TIME OF LESS THAN TEN HOURS. 